Facile preparation of nanoporous TiO2/MoOx composite and its high lithium storage performances as an anode material

Nanoporous TiO₂/MoO_x composite is easily fabricated via one-step mild dealloying of well-designed TiMoAl ternary alloy in alkaline solution. Selectively leaching the Al atom from the precursor alloy resulted in the formation of nanoporous TiO₂/MoO_x composite accompanied with the natural oxidation of Ti and Mo atoms. The TiO₂/MoO_x composite is comprised of interconnected nanoscaled network backbone and hollow channels with the ligament size around 40 nm and the pore size around 90 nm. Owing to the rich porosity and the incorporation of MoO_x, the as-made nanocomposite exhibits markedly enhanced lithium storage performances with superior reversible capacity, outstanding rate capability, and prominent cycling stabilities compared with the pure TiO₂. Especially, the reversible capacity remains about 321.6 and 167.5 mA h g^?1 at the rate of 300 and 1000 mA g^?1, respectively, after long cycling up to 500 times. Benefitting from the unique performance and facile preparation, the TiO₂/MoO_x composite holds promising application potential as an anode material in lithium-ion batteries.     

Enhanced electrochemical lithium storage performance of Mg2FeH6 anode with TiO2 coating

Light-weight metal hydrides are potential high-capacity conversion anode materials for lithium-ion batteries, but the poor reaction reversibility and cyclic stability of hydride anodes need to be improved. In this work, the ternary hydride Mg₂FeH₆ was composited with the graphite (G) by ball-milling, and the Mg₂FeH₆-G composite electrode was further coated with amorphous TiO₂ film by magnetron sputtering. The resultant Mg₂FeH₆-G/TiO₂ electrode exhibited a stable charge capacity of 412 mAh g^?1 over 100 cycles, which is much higher than 46 mAh g^?1 at 20th cycle for the pure Mg₂FeH₆ electrode, or 185 mAh g^?1 at 100th cycle for the Mg₂FeH₆-G electrode. There is only little capacity degradation after 20 cycles for the Mg₂FeH₆-G/TiO₂ electrode and the charge capacity retention is 84.7% after 100 cycles. The remarkable improvement in the cyclic stability of Mg₂FeH₆-G/TiO₂ electrode is mainly attributed to the dense TiO₂ coating that maintains the structural integrity of electrode during cycling. The TiO₂ coating also prevents the direct contact of high active LiH/MgH₂ with the liquid electrolyte, and thus ensures the high reversibility of conversion reaction of MgH₂ during cycling.     

One step electrodeposition of V2O5/polypyrrole/graphene oxide ternary nanocomposite for preparation of a high performance supercapacitor

A new ternary nanocomposite based on graphene oxide (GO), polypyrrole (PPy) and vanadium pentoxide (V₂O₅) is obtained via one-step electrochemical deposition process. Electrochemical deposition of V₂O₅, PPy and GO on a stainless steel (SS) substrate is conducted from an aqueous solution containing vanadyl acetate, pyrrole and GO to get V₂O₅/PPy/GO nanocomposite. Characterization of the electrode material is carried out by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and atomic force microscopy (AFM). The electrochemical performance of the as-prepared nanocomposite is evaluated by different electrochemical methods including cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy (EIS) in 0.5 M Na₂SO₄ solution. Remarkably, V₂O₅/PPy/GO nanocomposite shows a specific capacitance of 750 F g^?1 at a current density of 5 A g^?1, which is far better than PPy (59.5 F g^?1), V₂O₅/PPy (81.5 F g^?1) and PPy/GO (344.5 F g^?1). Furthermore, V₂O₅/PPy/GO maintains 83% of its initial value after 3000 cycles, which demonstrates good electrochemical stability of the electrode during repeated cycling. These results demonstrate that the combination of electrical double layer capacitance of GO and pseudocapacitive behavior of the PPy and V₂O₅ can effectively increase the specific capacitance and cycling stability of the prepared electrode. Also, a symmetric supercapacitor device assembled by V₂O₅/PPy/GO nanocomposite yielded a maximum energy density of 27.6 W h kg^?1 at a power density of 3600 W kg^?1, and a maximum power density of 13680 W kg^?1 at an energy density of 22.8 W h kg^?1.     

Old-loofah-derived hard carbon for long cyclicity anode in sodium ion battery

Hard carbon was prepared via the carbonization of the old loofah sponge at 800 °C for 1 h in the inert N₂ atmosphere for sodium ion battery (SIB) anode. The resultant old-loofah-derived hard carbon was investigated by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), Raman, galvanostatic charge/discharge, cyclic voltammetry (CV) and alternating current (AC) impedance. The results suggested that the old-loofah-derived hard carbon powders consisted of many irregular micro-particles with the mean particle size of 12 μm. Furthermore, the old-loofah-derived hard carbon anode also delivered satisfactory electrochemical performances in SIB. For example, the initial discharge specific capacity was as high as about 695 mAh g^?1 at 25 mA g^?1, and the reversible discharge specific capability after 1000 cycles was still about 171 mAh g^?1 even at 1000 mA g^?1, indicating long cycle stability and the promising feasibility of the old-loofah-derived hard carbon anode. The disordered micro-structure and large interlayer distance may jointly contribute into the satisfactory electrochemical performances.     

Growth of polyaniline on rGO-Co3S4 nanocomposite for high-performance supercapacitor energy storage

Recently, since the supercapacitors have drawn considerable attention, a vast study have been triggered in order to develop efficient electrodes for responding to the increasing demand of supercapacitors. In this report, a possible approach have been used to prepare a ternary nanocomposite, polyaniline/reduced graphene oxide-cobalt sulfide (PANI/rGO-Co₃S₄). At first, a simple and inexpensive hydrothermal route has been used for the preparation of cobalt sulfide (Co₃S₄) on the surface of graphene oxide sheets (rGO-Co₃S₄). Then, the polyaniline nanorods have been flourished on the surface of rGO-Co₃S₄ sheets via in situ chemical polymerization of aniline which was synergistically adjoined to the graphene surface. Polyaniline has uniformly covered the surface of the rGO-Co₃S₄ due to the rational combination of two components. Combining of PANI with rGO-Co₃S₄ electrode material amplify its electrochemical efficiency in terms of a high specific capacitance of 767 F g^?1 at 1 A g^?1 and 81.7% of specific capacitance maintenance after 5000 cycles due to the creation of synergistic effect. Therefore, the ternary nanocomposite of PANI/rGO-Co₃S₄ provides a new promising pathway for the expanding of high-performance electrode materials for supercapacitors.     

Effects of annealing temperature on the structure and properties of the LaY2Ni10Mn0.5 hydrogen storage alloy

The effects of annealing at 1123, 1148, 1173 and 1198 K for 16 h on the structure and properties of the LaY₂Ni₁₀Mn_0.5 hydrogen storage alloy as the active material of the negative electrode in nickel–metal hydride (Ni–MH) batteries were systematically investigated by X-ray diffraction (XRD), scanning electron microscopy linked with an energy dispersive X-ray spectrometer (SEM–EDS), pressure-composition isotherms (PCI) and electrochemical measurements. The quenched and annealed LaY₂Ni₁₀Mn_0.5 alloys primarily consist of Ce₂Ni₇- (2H) and Gd₂Co₇-type (3R) phases. The homogeneity of the composition and plateau characteristics of the annealed alloys are significantly improved, and the lattice strain is effectively reduced. The alloys annealed at 1148 K and 1173 K have distinctly greater hydrogen storage amounts, 1.49 wt% (corresponding to 399 mAh g^?1 in equivalent electrochemical units) and 1.48 wt%, respectively, than the quenched alloy (1.25 wt%, corresponding to 335 mAh g^?1 in equivalent electrochemical units). The alloys annealed at 1148 K and 1173 K have relatively good activation capabilities. The annealing treatment slightly decreases the discharge potentials of the alloy electrodes but markedly increases their discharge capacity. The maximum discharge capacities of the annealed alloy electrodes (372–391 mAh g^?1) are greater than the extreme capacity of the LaNi₅-type alloy (370 mAh g^?1). The cycling stability of the annealed alloy electrodes was improved.     

Core/shell Fe3O4@Fe encapsulated in N-doped three-dimensional carbon architecture as anode material for lithium-ion batteries

Core-shell Fe₃O₄@Fe nanoparticles embedded into porous N-doped carbon nanosheets was prepared by a facile method with NaCl as hard-template. The three-dimensional carbon architecture built by carbon nanosheets enhance the conductivity of the encapsulated Fe₃O₄@Fe nanoparticles and strengthen the structure stability suffering from volume expansion during extraction and insertion of lithium ions. Rich Pores enhance the surface between electrode and electrolyte, which short the transmission path of ions and electrons. The core-shell structure with Fe as core further improves charge transferring inside particles thus lead to high capacity. The as-prepared Fe₃O₄@Fe/NC composite displays an irreversible discharge capacity of 839 mAh g^?1 at 1 A g^?1, long cycling life (722.2 mAh g^?1 after 500th cycle at 2 A g^?1) and excellent rate performance (1164.2 and 649.2 mAh g^?1 at 1 and 20 A g^?1, respectively). The outstanding electrochemical performance of the Fe₃O₄@Fe/NC composite indicates its application potential as anode material for LIBs.     

Electrochemical properties of Ti2Ni hydrogen storage alloy

In this paper, the long cycling behavior, the kinetic and thermodynamic properties of Ti₂Ni alloy used as negative electrode in nickel-metal hydride batteries have been studied by different electrochemical techniques. Several methods, such as, galvanostatic charge and discharge, the constant potential discharge and the potentiodynamic polarization are applied to characterize electrochemically the studied alloy. The studied electrodes are observed before and after electrochemical tests at different temperatures by scanning electron microscopy.The amorphous Ti₂Ni is activated after five cycles and the achieved maximum discharge capacity is about 67 mAh g^?1 at ambient temperature. Despite the low values of the maximum discharge capacity and the cycling stability (17%) and the steep decrease of the discharge capacity after activation, this alloy conserves a good stability lifetime during a long cycling. A good correlation is observed between the evolution of the discharge capacity and those of the redox parameters during a long cycling.The enthalpy change, the entropy change and the activation energy of the formation reaction of the Ti₂Ni metal hydride are evaluated electrochemically. The found values of the enthalpy change, the entropy change and the activation energy are about ?43.3 kJ mol^?1, 51.7 J K^?1 mol^?1 and 34.9 kJ mol^?1, respectively.     

Electrochemical performance of Li4Ti5O12/carbon nanotubes/graphene composite as an anode material in lithium-ion batteries

A three-dimensional Li₄Ti₅O₁₂/carbon nanotubes/graphene composite (LTO-CNT-G) was prepared by ball-milling method, followed by microwave heating. The as-prepared LTO-CNT-G composite as anode material in lithium-ion battery exhibited superior rate capability and cycle performance under relative high current density compared with that of Li₄Ti₅O₁₂/CNTs (LTO-CNT) and Li₄Ti₅O₁₂/graphene (LTO-G) composites. Graphene nanosheets and CNTs were used to construct 3D conducting networks, leading to faster electron transfer and lower resistance during the lithium ion reversible reaction, which significantly enhanced the electrochemical activity of LTO-CNT-G composite. The synergistic effect of graphene and CNTs can greatly improve the rate capability and cycling stability of Li₄Ti₅O₁₂-based anodes. The LTO-CNT-G composite exhibited a high initial discharge capacity of 172 mAh g^?1 at 0.2 C and 132 mAh g^?1 at 20 C, as well as an excellent cycling stability. The electrochemical impedance spectroscopy demonstrated that the LTO-CNT-G composite has the smallest charge-transfer resistance compared with the LTO-CNT and LTO-G composites, indicating that the fast electron transfer from the electrolyte to the LTO-CNT-G active materials during the lithium ion intercalation/deintercalation owing to the three-dimensional networks of graphene and CNTs.     

Facile construction of self-assembled Cu@polyaniline nanocomposite as an efficient noble-metal free cocatalyst for boosting photocatalytic hydrogen production

Photocatalytic Hydrogen production via water splitting is considered a sustainable ecofriendly pathway to replenish the current and future energy demands. In this study, the self-assembly synthesis of Cu nanospheres (～8 nm) surrounded by a thin conductive layer of polyaniline (Cu@PANI) was rationally engineered via in?situ polymerization. Afterward, it was successfully deposited onto the TiO₂ surface to improve the photocatalytic activities for hydrogen production. The optimal Cu@PANI/TiO₂ ternary photocatalyst produced a substantial hydrogen generation rate (HGR) of 17.7 mmol h^?1 g^?1, 207-fold higher than that of bare TiO₂. The performance was considerably improved compared with (Cu–TiO₂)/PANI and (PANI-TiO₂)/Cu composites prepared by changing the deposition sequence of Cu and PANI. Such an improved activity was because of multiple transferring paths of photogenerated electrons in the composite. Interestingly, the as-prepared ternary photocatalyst exhibited superior hydrogen evolution compared with the binary hybrids (Cu/TiO₂ and PANI/TiO₂). The exceptional performance of Cu@PANI/TiO₂ could be understood considering the distinctive electrical conductivity of PANI and heterojunction formed between PANI and TiO₂, as well as the merits of the Schottky junction constructed between Cu and PANI. These superior features could efficiently suppress the recombination rate of the photogenerated electron–hole pairs and maximize the photocatalytic activity. This study provides new insights for understanding the effect of electron transfer pathways on photocatalytic activities.     

Construction of ternary hybrid layered reduced graphene oxide supported g-C3N4-TiO2 nanocomposite and its photocatalytic hydrogen production activity

Reduced graphene oxide (rGO) supported g-C₃N₄-TiO₂ ternary hybrid layered photocatalyst was prepared via ultrasound assisted simple wet impregnation method with different mass ratios of g-C₃N₄ to TiO₂. The synthesized composite was investigated by various characterization techniques, such as XRD, FTIR, Raman Spectra, FE-SEM, HR-TEM, UV vis DRS Spectra, XPS Spectra and PL Spectra. The optical band gap of g-C₃N₄-TiO₂/rGO nanocomposite was found to be red shifted to 2.56 eV from 2.70 eV for bare g-C₃N₄. It was found that g-C₃N₄ and TiO₂ in a mass ratio of 70:30 in the g-C₃N₄-TiO₂/rGO nanocomposite, exhibits the highest hydrogen production activity of 23,143 μmol g^?1h^?1 through photocatalytic water splitting. The observed hydrogen production rate from glycerol-water mixture using g-C₃N₄-TiO₂/rGO was found to be 78 and 2.5 times higher than g-C₃N₄ (296 μmol g^?1 h^?1) and TiO₂ (11,954 μmol g^?1 h^?1), respectively. A direct contact between TiO₂ and rGO in the g-C₃N₄-TiO₂/rGO nanocomposite produces an additional 10,500 μmol g^?1h^?1 of hydrogen in 4 h of photocatalytic reaction than the direct contact between g-C₃N₄ and rGO. The enhanced photocatalytic hydrogen production activity of the resultant nanocomposite can be ascribed to the increased visible light absorption and an effective separation of photogenerated electron-hole pairs at the interface of g-C₃N₄-TiO₂/rGO nanocomposite. The effective separation and transportation of photogenerated charge carriers in the presence of rGO sheet was further confirmed by a significant quenching of photoluminescence intensity of the g-C₃N₄-TiO₂/rGO nanocomposite. The photocatalytic hydrogen production rate reported in this work is significantly higher than the previously reported work on g-C₃N₄ and TiO₂ based photocatalysts.     

Vertically-heterostructured TiO2-Ag-rGO ternary nanocomposite constructed with {001} facetted TiO2 nanosheets for enhanced Pt-free hydrogen production

TiO₂ nanosheets with high ratio of {001} facets were coupled with reduced graphene oxide (rGO) nanosheets through the link of silver (Ag) nanoparticles, forming a novel ternary nanocomposite photocatalyst with a vertical heterostructure, TiO₂-Ag-rGO. The vertical anchoring of TiO₂-Ag nanosheets between rGO sheets was confirmed by transmission electron microscopy (TEM), Raman spectroscopy, energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). Due to excellent separation of electron-hole pairs in the TiO₂ nanosheets, enhanced electron transfer to rGO via Ag nanoparticles, the TiO₂-Ag-rGO nanocomposite exhibited an outstanding performance in photocatalytic hydrogen production, with a hydrogen production rate of 593.56 μmol g^?1 h^?1. This study provides new insights to the development of Pt-free photocatalysts for hydrogen production.     

Nanostructured Bi2O3@TiO2 photocatalyst for enhanced hydrogen production

Here we report on Bi₂O₃ clusters immobilized on anatase TiO₂ nanostructures for an enhanced rate of photocatalytic H₂ evolution. Structural, morphological, and optical properties of the Bi₂O₃@TiO₂ nanocomposite (BT) were characterized by a series of techniques including X-ray diffraction, high resolution transmission electron microscopy, X-ray photoelectron spectroscopy, diffuse reflectance spectroscopy and electrochemical impedance spectroscopy. The catalytic H₂ evolution experiments were carried out under different light sources: natural solar light, LED UV (365 ± 5 nm) and LED visible (420 ± 5 nm) light source. Under the solar light a pristine anatase TiO₂ nanostructured (TNS) catalyst generated 4.20 mmol h^?1 g^?1, whereas in the presence of Bi₂O₃@TNS showed much higher H₂ production 26.02 mmol h^?1 g^?1. The photocatalytic activity of the BT and its reproducible performance for five recycles is ascribed to an efficient separation of photogenerated charge carriers. A plausible reaction mechanism for the H₂ generation is proposed.     

Facile synthesis of Ti3+ doped Ag/AgITiO2 nanoparticles with efficient visible-light photocatalytic activity

We successfully synthesized novel Ti³⁺ doped TiO₂ and Ti³⁺ doped Ag/AgITiO₂ nanoparticles with efficient visible-light photocatalytic activity for hydrogen production by facile one-step solvothermal method. The as-prepared Ti³⁺ doped TiO₂ nanoparticles displayed excellent visible-light absorption and visible-light driven hydrogen production activity (115.3 μmol g^?1 h^?1), while the commercial TiO₂ had no visible-light response. Moreover, the as-prepared Ti³⁺ doped Ag/AgITiO₂ nanoparticles in this experiment showed highly enhanced visible-light absorption and efficient visible-light driven activity for hydrogen (571.0 μmol g^?1 h^?1), which was 4.95 times as high as that of the as-prepared TiO₂ nanoparticles. And the surface areas of the as-prepared TiO₂ and Ti³⁺ doped Ag/AgITiO₂ catalysts were up to 138.829 m² g^?1 and 102.988 m² g^?1, much higher than that of the commercial TiO₂ (55.516 m² g^?1). Finally, the visible-light photocatalytic mechanism of the Ti³⁺ doped Ag/AgITiO₂ nanoparticles for hydrogen generation was also proposed in detail.     

CNF-grafted carbon fibers as a binder-free cathode for LithiumOxygen batteries with a superior performance

In this work, we report the significant enhancement of the electrochemical performance and flexibility of a lithium–oxygen battery by introducing a free-standing, binder-free carbon nano-fibers (CNF) grafted carbon paper cathode with a bimodal pore architecture. The small pore structures (～100 nm) accommodated Li₂O₂, and the large pore structures (～10 μm) enabled effective oxygen diffusion without clogging the pores. This kind of cathode overcame some troubles of the cathode prepared by spraying coating method, such as the low utilization of substrate surface, the unreasonable aperture structure and the aggregation of active carbon material. As a result, this electrode structure imparted stability to active sites during the recovery of discharge products to the initial state, providing long-term cyclability of more than 800 cycles in a 1 M LiTFSI/TEGDME electrolyte system. In addition, the battery output a discharge capacity as high as 20000 mAh g^?1 at 468 mA g^?1 and exhibited a charge/discharge rate as high as 1136 mA g^?1 (0.57 mA cm^?2). The test results suggest that these CNF-grafted carbon papers have the potential to be used for oxygen/air electrodes for next-generation lithium-oxygen batteries, though the present results need to be improved to achieve performance of practical significance, namely with regard to (i) cathode mass loading to get higher areal capacity, and (ii) cycling performance at higher current density.     

Polyaniline-silver-manganese dioxide nanorod ternary composite for asymmetric supercapacitor with remarkable electrochemical performance

Metal oxide incorporated with a conductive polymer have shown great potential as high-performance energy storage devices. In this report, polyaniline wrapped silver decorated manganese dioxide (PANI/Ag@MnO₂) nanorods were successfully synthesized and used as positive electrode material. Cyclic voltammetry, galvanostatic charge discharge and electrochemical impedance spectroscopy were employed to investigate the electrochemical activities. The overall result demonstrates that as prepared PANI/Ag@MnO₂ nanorod performed better supercapacitor activities compared to Ag@MnO₂ and pure MnO₂. The PANI/Ag@MnO₂ nanocomposite exhibited a high specific capacitance of 1028.66 F g^?1 at a current density of 1 A g^?1 (nearly close to the theoretical capacitance of MnO₂). A detail investigation of the synergic effect of PANI, Ag and MnO₂ on electrochemical properties is presented sequentially. The assembled (PANI/Ag@MnO₂//AC) asymmetric supercapacitor device showed a high energy density of 49.77 W h kg^?1 at power density of 1599.75 W kg^?1. The facile and cost-effective production of PANI/Ag@MnO₂ demonstrates a high specific capacitance and energy density with long life cycle introduces this material as a prospective candidate for energy management.     

Mesoporous polyaniline/TiO2 microspheres with core-shell structure as anode materials for lithium ion battery

Mesoporous polyaniline/anatase TiO₂ composite microspheres with the core-shell structure for lithium-ion battery applications are prepared via a facile hydrothermal route. The structure of as-prepared sample is characterized by electron microscopy (TEM), and scanning electron microscopy (SEM), X-ray diffraction (XRD), and Brunauer-Emmett-Teller (BET) surface area. It is suggested that the formation of the core-shell structure can be designated as a two-step assembly process induced by the polymerization of the aniline. The electrochemical tests demonstrate that the discharge capacity of the as-prepared polyaniline/anatase TiO₂ microspheres can be stably retained at 157.1 mAh g⁻¹ after 50th cycle at the high current density of 1500 mA g⁻¹. The high rate performance of the as-prepared sample at various current densities from 200 to 2000 mA g⁻¹ is also investigated. The discharge capacity of 123.9 mAh g⁻¹ can be obtained at the high current density of 2000 mA g⁻¹, which is about 73.4% of that at the low current density of 200 mA g⁻¹ upon cycling, indicating that the as-prepared sample can endure great changes of various current densities to retain a good stability due to the core shell mesoporous structure.     

Highly stabilized Ag2O-loaded nano TiO2 for hydrogen production from glycerol: Water mixtures under solar light irradiation

Nano TiO₂ prepared by a hydrothermal method and silver-loaded nano TiO₂ prepared by impregnation were studied for the photocatalytic production of hydrogen from glycerol:water mixtures. The structural characteristics were revealed using XRD, EDAX, DRS, TEM, XPS, BET surface area and Raman techniques. The photocatalytic hydrogen production has been investigated under solar light irradiation. Effects of nano TiO₂ calcination temperature, silver loading, photocatalyst content, light source and Ag oxidation state on hydrogen production have been systematically studied. Maximum hydrogen production of 200 μmol h^?1 g^?1 is observed on 4wt% silver-loaded nano TiO₂ catalyst in pure water and the maximum hydrogen production of 7030 μmol h^?1 g^?1 is observed on 3wt% silver-loaded nano TiO₂ catalyst in glycerol: water mixtures. Silver-loaded nano TiO₂ reduced and photodeposited catalysts show similar hydrogen production activities in glycerol: water mixtures under solar irradiation. The optimum catalyst modified with conducting carbon materials (graphene oxide, graphene, carbon nanotubes) by a solid-state dispersion method were also studied for hydrogen production under solar light irradiation. Compared with pure nano TiO₂, a 3wt% silver-loaded nano TiO₂/graphene composite exhibited an approximately 17-fold enhancement of hydrogen production leading to hydrogen production rates of 12,100 μmol h^?1 g^?1. Based on the characterization results and hydrogen production activity on these catalysts, a structure–activity correlation has been proposed wherein the interacting Ag₂OAg phases on the surface of nano TiO₂ play an important role in maintaining a high hydrogen production activity under solar irradiation.     

Facile synthesis of nitrogen-doped Sn@NC composites as high-performance anodes for lithium-ion batteries

Owing to its high capacity of 994 mAh g^?1, low cost, and environmental friendliness, tin (Sn) is considered as an advanced anode material for high-capacity lithium-ion batteries (LIBs). Here, a facile strategy to fabricate core-shell structured Sn@NC composites with one-step and large-scale production is introduced in a liquid-phase reaction under room temperature. When used as anode materials for LIBs, the optimal Sn@NC composite delivers a high reversible discharge capacity of 761.2 and 476 mAh g^?1 at a current density of 200 and 1000 mA g^?1 after 200 cycles, respectively. A high capacity of 328.3 mAh g^?1 can also be obtained even at a current density of 2000 mA g^?1. The excellent cycling stability and rate performance of the composite can be ascribed to the synergistic effect of the nanometer size of Sn powder and porous structure of the carbon shell, both of which can effectively reduce the absolute volume change of electrode during the repeated charge-discharge cycles, and thus lead to excellent electrochemical performances at both rate capability and cycling life.     

Chemical bath deposition synthesis of TiO2/Cu2O core/shell nanowire arrays with enhanced photoelectrochemical water splitting for H2 evolution and photostability

In this study, we have developed a facile chemical bath deposition (CBD) method to grow p-type Cu₂O nanoparticles on n-type TiO₂ nanowire arrays (TiO₂ NWAs) to fabricate TiO₂/Cu₂O core/shell heterojunction nanowire arrays (TiO₂/Cu₂O core/shell NWAs). When used as photoelectrode, the fabricated TiO₂/Cu₂O core/shell NWAs show improved photoelectrochemical (PEC) water splitting activity to pure TiO₂ NWAs. The effects of the CBD cycle times on the PEC activities have been studied. The TiO₂/Cu₂O core/shell heterojunction nanowire array photoelectrode prepared by cycling 5 times in the CBD process achieves the highest photocurrent of 2.5 mA cm^?2, which is 2.5 times higher than that of pure TiO₂ NWAs. In addition, the H₂ generation rate of this photoelectrode reaches to 32 μmol h^?1 cm^?2, 1.7 times higher than that of pure TiO₂ NWAs. Furthermore, the TiO₂/Cu₂O core/shell heterojunction nanowire array photoelectrode shows excellent photostability and achieves a stable photocurrent of over 2.3 mA cm^?2 during long light illumination time of 5 h. The enhanced photocatalytic activity of TiO₂/Cu₂O core/shell heterojunction nanowire array photoelectrode is attributed to the synergistic actions of TiO₂ and Cu₂O for improving visible light harvesting, and efficient transfer and separation of photogenerated electrons and holes.